Generating images for at least two displays in image-guided surgery

ABSTRACT

A system, in particular for image-guided surgery, comprising: at least two display devices; a position determinator for determining the relative position of the display devices; and an image generator for generating images, which are to be displayed by the display devices, in accordance with the determined relative position.

This application is a divisional of U.S. patent application Ser. No.13/806,361 filed Dec. 21, 2012 that was a U.S. National phase ofInternational Application No. PCT/EP2010/059140 filed Jun. 28, 2010, theentire contents of which are incorporated herein by reference

TECHNICAL FIELD

The present invention relates to a system which is in particular fordisplaying images, in particular in the medical field, in particular forimage-guided surgery, comprising at least two display devices, and to amethod for generating images to be displayed by the display devices.

BACKGROUND

Systems for image-guided surgery are known and commercially available.Such systems comprise at least one display device, such as a monitor ora screen, for displaying information which aids the surgeon duringsurgery. Some of these systems comprise two display devices. The presentinvention relates to generating images to be displayed by such displaydevices.

The present invention is directed to a system, in particular forimage-guided surgery, comprising at least one and in particular at leasttwo display devices. In particular, the system comprises a positiondeterminator for determining the position, in particular the relativeposition, of the display device(s). In particular, the system alsocomprises an image generator for generating images, which are to bedisplayed by the display device(s), in accordance with the determinedposition, in particular the relative position. Generating images inaccordance with the determined position means that the generated imagesdepend on the determined position. This means in particular that theimage generator is capable of generating independent images for each ofthe display devices.

The image generator can for example generate the same image for all thedisplay devices, the same image for some of the image devices while theother display devices display different images, or a different image foreach display device. In particular, the decision as to which image is tobe generated for a particular display device depends on the position, inparticular the relative position, of the display devices. If more thantwo display devices are provided, the term “relative position” comprisesa set of relative positions which comprises at least one position ofeach of the display devices relative to another of the display devices.

In this document, the term “position” means a combination of locationand alignment. The location means the point in space at which an objectis located in up to three spatial or translational dimensions. Thealignment or orientation means the rotational angle at which an objectis positioned in up to three rotational dimensions. The term “relativeposition” means the relative spatial and/or rotational displacement,each in up to three dimensions, of two objects such as display devices.The relative position between two objects can be determined eitherdirectly or indirectly. Indirectly determining it means for exampledetermining the positions of two objects relative to a common referenceand determining the relative position between the objects from therelative positions of the objects and the reference.

In accordance with the invention, a method of generating images for atleast one and in particular at least two display devices (for instance,in a system for image-guided surgery) comprises the steps of determiningthe position, in particular the relative position, of the displaydevice(s) and generating images, which are to be displayed by thedisplay device(s), in accordance with the determined position, inparticular the relative position.

In this document, the expression “observing a display device” meansobserving the image displayed by the display device, hence if a personcan see, view or observe a display device, this means that this personcan see, view or observe the image displayed by the display device.

In one arrangement, a viewer can see several or all of the displaydevices. In this case, it is advantageous to display different images oneach of the display devices which can be seen. An enlarged view of anobject or a graphical user interface of an application is for examplespread over several display devices. In another example, graphical userinterfaces of multiple applications are spread over several displaydevices. It is of course also possible to duplicate the same image onseveral display devices.

In another configuration, each display device or sub-group of displaydevices can be viewed by a different person or group of persons. In thiscase, the preferred scenario is to duplicate the same image on severaldisplay devices. It is also of course still possible to generatedifferent images for the display devices, for example if differentpersons are to be provided with different information.

In the present invention, the content displayed on at least two displaydevices, i.e. exactly two or more than two (for instance, three or four)display devices, is automatically adjusted in accordance with therelative position of the display devices. An image displayed on onedisplay device is for example enlarged and displayed on two or moredisplay devices if one or more other display devices are placed next tothe first display device at a distance which is less than a thresholdvalue. If the distance between the first display device and anotherdisplay device(s) is increased above the threshold value, then the imageis no longer displayed in the enlargement and another image, such as thegraphical user interface of an application, is displayed on the otherdisplay device.

In one embodiment, the system comprises an adjustable mounting for adisplay device, the mounting consisting of multiple elements, whereintwo adjoining elements are connected via an adjustable joint. Typicalexamples of such mountings are arms or carrier arms. The system alsocomprises at least one sensor for detecting the state of at least onejoint. Preferably, one sensor is provided for each joint. The state of ajoint represents the relative position of the elements connected by saidjoint. If the joint is a pivot bearing, then the sensor output is anangle. If the joint is a bearing which allows a translational movement,then the sensor output is a distance. The position determinator cancalculate the position of the display device, in particular the relativeposition of the display device relative to a reference such as the baseof a mounting, from the states of all the joints of the mounting and thestructure of the mounting. If this information is known for more thanone display device, then the relative position of these display devicescan be determined. In general, the relative position is determined fromthe state of at least one joint which connects adjoining elements of amounting device for a display device.

In another embodiment, a marker device is attached to at least onedisplay device, wherein the position determinator is configured todetermine the relative position from the position of the marker device.In terms of a method, the relative position is determined from thepositions of marker devices attached to the display devices. Theposition determinator can determine the relative position of the displaydevices from the relative position of the marker devices attached to thedisplay devices and the known relative positions of the display devicesand the respectively attached marker devices.

A marker device can for example be a reference star or a pointer or oneor more (individual) markers which are in a predetermined spatialrelationship. This predetermined spatial relationship is in particularknown to a navigation system and for example stored in a computer of thenavigation system.

It is the function of a marker to be detected by a marker detectiondevice (for example, a camera or an ultrasound receiver), such that itsspatial position (i.e. its spatial location and/or alignment) can beascertained. The detection device is in particular part of a navigationsystem. The markers can be active markers. An active marker can forexample emit electromagnetic radiation and/or waves, wherein saidradiation can be in the infrared, visible and/or ultraviolet spectralrange. The marker can also however be passive, i.e. can for examplereflect electromagnetic radiation in the infrared, visible and/orultraviolet spectral range. To this end, the marker can be provided witha surface which has corresponding reflective properties. It is alsopossible for a marker to reflect and/or emit electromagnetic radiationand/or waves in the radio frequency range or at ultrasound wavelengths.A marker preferably has a spherical and/or spheroid shape and cantherefore be referred to as a marker sphere; markers can also, however,exhibit a cornered—for example, cubic—shape.

In another embodiment, the system comprises at least one camera whichobserve(s) the display devices, wherein the position determinator isconfigured to determine the relative position from the output image ofthe at least one camera. In terms of the method, the relative positionis determined from at least one output image of at least one camera,wherein the output image shows the display devices. The camera capturesan image which shows the display devices. The relative position of thedisplay devices can be calculated using image analysis. Preferably, allthe display devices are within the field of view of a camera.Alternatively, different display devices can be observed by differentcameras. The relative position of the display devices can then bedetermined from the output images of multiple cameras. The camera can bea 2D camera or a stereoscopic camera, such as for example a stereoscopiccamera of a medical navigation system. A stereoscopic camera can also beused as a marker detection device.

In another embodiment of the present invention, the system comprises acamera which is attached to a display device, wherein the positiondeterminator is configured to determine the relative position from theoutput image of the camera. In terms of the method, the relativeposition is determined from at least one output image of a camera whichis attached to a display device. Such a camera observes the surroundingsof the display device. The position of the camera can be calculatedusing image analysis. In one example, a 3D model of the surroundings isprovided to a position determinator, and a virtual image is rendered fora virtual location and a virtual perspective, i.e. a virtual cameraposition. If the rendered image matches the camera output image, thenthe position of the camera matches the virtual position.

Using the camera which is attached to the display device, it is possibleto detect incident light upon the camera, and therefore incident lightupon the display device. Unwanted reflections of the incident light canbe determined from the detection result. The effects of thesereflections can be reduced by adapting the displayed image and/or byrepositioning the display device. In general, any other device which issuited to detect electromagnetic waves in the visual spectrum can beused instead of a camera. In particular, a device or multitude of suchdevices, each receiving waves from a defined solid angle, can be used.An example for such a device is a photo detector or photo resistorprovided with a lens defining a solid angle from which incident light isdetected.

In another embodiment according to this invention or an additionalinvention, the system comprises at least one or at least two displaydevices and a viewer detector, such as an RFID reader or camera, fordetecting a viewer who is viewing a display device, wherein the imagegenerator is configured to generate an image for this display device inaccordance with the determined viewer. In this embodiment, the positiondetermining means is optional. A viewer detector can be configured andpositioned to determine the viewer or viewers of one or more displaydevices. In a preferred embodiment, there is a dedicated viewer detectorassigned to each display device for which the viewer is to be detected.In terms of the method, a viewer who is viewing a display device isdetermined, and the image to be displayed by this display device isgenerated in accordance with the determined viewer. In general, a viewerwho is viewing one, two or more than two display devices can beidentified, and/or one or more viewers of a display device can beidentified.

Each potential viewer for example carries an RFID chip having a uniqueID which can be read out by the RFID reader. The viewer who is viewingthe display device is thus identified. In particular, a directed antennais used to detect RFID chips only in the area from which thecorresponding display device can be viewed. Additionally oralternatively, a camera—for example, a camera which is attached to adisplay device—captures an image of the viewer, and the viewer is thenidentified by image analysis, for example by comparing the image of theviewer with reference images which are in particular stored in areference image database or by face recognition. In face recognition, apossible approach is to detect individual facial components and/orfeatures of the person to be identified, such as the distance betweenthe eyes or the distance between an eye and the nose, and so on.

Once the viewer has been determined, the image generator generates oneor more images which are adapted to the needs of the determined viewerwho is viewing the display device or display devices. For example, thedisplay device or devices being viewed by a surgeon can then showinformation for navigating a medical instrument or can show medicalimages such as x-ray, CT or MRI images, while the display device ordevices being viewed by other operating room personnel can show medicalinformation such as the heart rate or pulse of the patient or an imageof a microscope. In addition to image generation depending on theviewer, or as an alternative, it is possible to configure a touch screenfunctionality depending on the identified viewer. For example, the touchscreen functionality is only provided to a person or group of personswhich is allowed to input or amend data. In general, the touch screenfunctionality of a display device can be enabled, disabled or configureddepending on the detected viewer, in particular in combination with thegeneration of the graphical user interface.

As an option, eye tracking can be performed on the output image of thecamera, in particular in combination with the viewer identification byimage analysis. In a particular embodiment, the result of the eyetracking can be used for determining whether or not a person which is ina position from which he or she could view the display device actuallydoes so. If the person could view more than one display devices, it canbe determined which of the display devices is actually viewed. Some datacan for example always be displayed on the display device which isactually viewed by the viewer.

In a specific embodiment, the system comprises: an adjustable mountingwhich consists of multiple elements, wherein two adjoining elements areconnected via an adjustable joint; and at least one actuator foradjusting the state of at least one joint. Accordingly, the methodcomprises the step of generating a drive signal for driving at least oneactuator in order to adjust the state of at least one joint whichconnects two adjoining elements of an adjustable mounting which holds adisplay device. A “drive signal” can also be an instruction to generatea drive signal, in particular if the method is implemented by a softwarewhich instructs a suitable means to generate the drive signal. Themounting can be adjusted using the actuators, in order to move thecorresponding display device to a desired position. This desiredposition is for example a position in which no reflections occur. Asmentioned above, the reflections are for example detected by a camerawhich is directed towards the display. The images generated by thecamera are analysed for reflections, and the position of the display isvaried so as to minimise the reflections. The actuators can also bedriven in such a way that the display device follows the movement of aviewer, such that the display device is always positioned such that itcan be viewed by the viewer. The position of the viewer can be detectedby one or more cameras which can be mounted on the display.

The system in accordance with the invention is in particular anavigation system. A navigation system, in particular a surgicalnavigation system, is understood to mean a system which can comprise: atleast one marker device; a transmitter which emits electromagnetic wavesand/or radiation and/or ultrasound waves; a receiver which receiveselectromagnetic waves and/or radiation and/or ultrasound waves; and anelectronic data processing device which is connected to the receiverand/or the transmitter, wherein the data processing device (for example,a computer) in particular comprises a processor (CPU), a working memory,advantageously an indicating device for issuing an indication signal(for example a visual indicating device such as a monitor and/or anaudio indicating device such as a loudspeaker and/or a tactileindicating device such as a vibrator) and advantageously a permanentdata memory, wherein the data processing device processes navigationdata forwarded to it by the receiver and can advantageously outputguidance information to a user via the indicating device. The navigationdata can be stored in the permanent data memory and for example comparedwith data which have been stored in said memory beforehand.

In one embodiment, at least one of the display devices comprises atouch-sensitive surface. This touch-sensitive surface can exhibit afunctionality which depends on the person viewing the display deviceand/or the relative position of the display devices.

The present invention also relates to a program which, when running on acomputer or when loaded onto a computer, causes the computer to performthe method as described above, and/or to a program storage medium onwhich the program is stored (in particular non-transitory), and/or to acomputer on which the program is running or into the memory of which theprogram is loaded, and/or to a signal wave, in particular a digitalsignal wave, carrying information which represents the program, whereinthe aforementioned program in particular comprises code means which areadapted to perform all the steps of the method as described above.

Within the framework of the invention, computer program elements can beembodied by hardware and/or software (this also includes firmware,resident software, micro-code, etc.). Within the framework of theinvention, computer program elements can take the form of a computerprogram product which can be embodied by a computer-usable orcomputer-readable storage medium comprising computer-usable orcomputer-readable program instructions, “code” or a “computer program”embodied in said medium for use on or in connection with theinstruction-executing system. Such a system can be a computer; acomputer can be a data processing device comprising means for executingthe computer program elements and/or the program in accordance with theinvention. Within the framework of this invention, a computer-usable orcomputer-readable medium can be any medium which can include, store,communicate, propagate or transport the program for use on or inconnection with the instruction-executing system, apparatus or device.The computer-usable or computer-readable medium can for example be, butis not limited to, an electronic, magnetic, optical, electromagnetic,infrared or semiconductor system, apparatus or device or a medium ofpropagation such as for example the Internet. The computer-usable orcomputer-readable medium could even for example be paper or anothersuitable medium onto which the program is printed, since the programcould be electronically captured, for example by optically scanning thepaper or other suitable medium, and then compiled, interpreted orotherwise processed in a suitable manner. The computer program productand any software and/or hardware described here form the various meansfor performing the functions of the invention in the exampleembodiments. The computer and/or data processing device can inparticular include a guidance information device which includes meansfor outputting guidance information. The guidance information can beoutputted, for example to a user, visually by a visual indicating means(for example, a monitor and/or a lamp) and/or acoustically by anacoustic indicating means (for example, a loudspeaker and/or a digitalspeech output device) and/or tactilely by a tactile indicating means(for example, a vibrating element or vibration element incorporated intoan instrument).

It is within the scope of the present invention to extract one or morefeatures of different embodiments or options to form a new embodiment orto omit features which are not essential to the present invention froman embodiment. In particular, images can be generated in accordance withthe identity of the viewer in a system comprising one display deviceonly and/or independently of the relative position between two or moredisplay devices.

BRIEF DESCRIPTION OF THE FIGURES

The present invention shall now be explained in more detail by referringto an example embodiment which is depicted in the attached figures,which show:

FIG. 1 a system for image-guided surgery, comprising two monitors;

FIG. 2 a schematic block diagram of the system of FIG. 1;

FIG. 3 the system of FIG. 1 in a first schematic scenario; and

FIG. 4 the system of FIG. 1 in a second schematic scenario.

DETAILED DESCRIPTION

FIG. 1 shows a system 1 which is designed to be used in image-guidedsurgery. The system 1 comprises two monitors 2 and 3 as exampleembodiments of display devices. The monitor 2 is attached to a base 4via an arm 5 which is used as an adjustable mounting. The monitor 3 isattached to the base 4 via an arm 6 which is used as an adjustablemounting. The monitors 2 and 3 can be respectively moved into desiredpositions using the arms 5 and 6. At all times, the monitors 2 and 3exhibit a relative position with respect to each other.

FIG. 2 shows a schematic block diagram of the system 1. The monitors 2and 3 are connected to a control unit 7. The control unit 7 comprises aposition determinator 8 and an image generator 9. The positiondeterminator 8 determines the relative position between the monitors 2and 3. The image generator 9 generates images which are to be displayedby the monitors 2 and 3. The image generator 9 can generate differentimages for each monitor or duplicate the same image on two or moremonitors, the latter resulting in cloned images.

In general, the position determinator 8 can be configured to determinethe relative position between the monitors not directly but rather fromthe relative position of each monitor as compared to a known reference.

FIG. 3 shows a first scenario in which a single person 10 or group ofpersons can see both the monitors 2 and 3. In addition, the arms 5 and 6are depicted in more detail.

As shown in FIG. 3, the arm 5 basically consists of two elements 5 a and5 b and a mounting bracket 5 c. The mounting bracket 5 c is fixed to themonitor 2 and connected to the element 5 b via a ball joint 5 e. Theball joint 5 e enables a rotational relative movement between thebracket 5 c and the element 5 b in two dimensions. The elements 5 b and5 a are connected via a pivot joint which enables a relative movementbetween these two elements in one rotational dimension. The element 5 ais connected to the base 4 via another pivot joint (not shown).

Similarly, the arm 6 basically consists of two elements 6 a and 6 b anda mounting bracket 6 c. The monitor 3 is affixed to the mounting bracket6 c. The mounting bracket 6 c and the element 6 b are connected via aball joint 6 e, while the elements 6 b and 6 a are connected via a pivotjoint 6 d. The element 6 a is also connected to the base 4 via anotherpivot joint (not shown).

For each joint, i.e. the joints 5 d, 5 e, 6 d, 6 e and the two jointsbetween the base 4 and the elements 5 a and 6 a, respectively, a sensoris provided which determines the current state, i.e. the position, ofthe respective joint and transmits this state to the positiondeterminator 8. The position determinator 8 can then calculate therelative position between the monitors 2 and 3 from the different statesof the joints and the known geometric structure of the arms 5 and 6.

In the present scenario, the position determinator 8 determines thatboth monitors 2 and 3 can be seen by the person 10, who is for example asurgeon. On the basis of this information, the image generator 9calculates the images to be displayed by the monitors 2 and 3 and sendsthe images to the corresponding respective monitors.

In one example, the graphical user interface of a software program isspread over the two monitors 2 and 3. In a second example, the graphicaluser interface of a first software is displayed on the monitor 2, and agraphical user interface of a second software is displayed on themonitor 3. In a third example, the graphical user interface of asoftware is displayed on the monitor 2, while medical data such as forexample image data generated by an x-ray, CT or MRI imaging apparatus orany other imaging apparatus are displayed on the monitor 3.

In one specific embodiment of the third example or in the general caseof two or more adjacent monitors, the previously described distributionacross the two monitors 2 and 3 is maintained as long as the distancebetween the monitors 2 and 3 is above a predefined threshold value, suchas for example 5 cm. If the monitors 2 and 3 are brought closer to eachother, resulting in a distance which is less than the threshold value,the medical image shown on the monitor 3 is enlarged and spread acrossthe monitors 2 and 3. If the distance between the monitors 2 and 3 issubsequently increased again, the image generator 9 returns to theprevious operating mode and displays the graphical user interface on themonitor 2 and the medical data on the monitor 3. In general, if two ormore monitors are adjacent and can be seen by the same person, the imagegenerator 9 generates the images to be displayed by these monitors inaccordance with the distance between the monitors. Adjacent monitors arein particular monitors which can be viewed by the same person and whichare in particular spaced apart by a distance which is smaller than athreshold value, such as for example the image size of a monitor. Analternative or additional criterion for monitors being adjacent is theangle between the display screens of the monitors. If this angle iszero, i.e. the screens are in the same or parallel planes, or below athreshold value, such as 45 degrees, 30 degrees, 20 degrees, 10 degreesor 5 degrees, then the monitors are considered adjacent.

Optionally, the image generator 9 generates an image for a displaydevice in accordance with the relative position between this displaydevice and an object, such as for example a patient or an operatingtable. This relative position can also be determined by the positiondeterminator 8. Information about the type and location of the surgery,with reference to the patient or operating table, is also optionallyprovided to the image generator 9, such that the images are alsogenerated in accordance with this information. If a display device isfor example positioned such that the surgeon can see the display device,then information relating to the actual surgery is displayed, whilegeneral information about the condition of a patient is displayed on adisplay device which is positioned towards other medical personnel, suchas for example a surgical nurse. If, for example, the image generator 9knows that surgery is being performed on the head of a patient and thata monitor is directed towards a position near the head, then informationrelevant to the surgeon is displayed. In other words, the person viewinga monitor is identified from the position which the monitor is facing orfrom which the monitor can be viewed, and from information as to theperson or persons who do or may be expected to remain at this position.

In the scenario shown in FIG. 4, the monitors 2 and 3 are facingdifferent persons or groups of persons. The monitor 2 is facing theperson 10, for example a surgeon, while the monitor 3 is facing a person11, such as for example a medical nurse or an observer. The positiondeterminator 8 identifies this scenario from the states of the joints ofthe arms 5 and 6. On the basis of this information, the image generator9 decides to display the same image, i.e. a duplicated image, on boththe monitors 2 and 3. Alternatively, the image generator 9 can beprogrammed to display different images on the monitors 2 and 3, forexample consisting of the same basic image, but supplemented byinformation which is of particular interest to the person viewing therespective monitor. The image generator 9 can be programmed while thesystem is being used, for example using an input device (not shown) suchas a touch-sensitive surface on one or more of the monitors.

In general, the relative position between a monitor and another object,such as a patient or an operating table, can be determined, for exampleby the position determinator 8. The images can then be generated by theimage generator 9 on the basis of this relative position. In thescenario shown in FIG. 4, the image generator 9 determines that themonitor 2 is facing a position at which the surgeon 10 is expected to bestanding, while the monitor 3 is facing away from the patient. From thisinformation, the image generator 9 knows which information to display onwhich monitor.

As an alternative to or in combination with the information about therelative position between a monitor and another object, the images canalso be generated on the basis of information about the identity of aviewer who is viewing the monitor. The viewer can for example reveal hisor her identity to the control unit 7 by inputting this information viaa keyboard or by swiping a keycard through a reader. The viewer can alsobe wearing an RFID chip which is read out by an RFID reader. The viewercan also be identified biometrically.

As an alternative to the sensors which detect the states of the jointsof the arms 5 and 6, a marker device can be attached to a monitor. Amarker detection device (not shown), such as for example a stereoscopiccamera of a medical navigation system, detects the positions of themarkers and provides this information to the control unit 7. Theposition determinator 8 then calculates the relative position betweenthe monitors 2 and 3 from the positions of the markers and the knownrelative position between each marker and the monitor which it isattached to.

In another alternative, one or more cameras (not shown) are provided ina position which is such that each camera observes one or more,preferably all, of the monitors. By analysing the output image or imagesof the camera or cameras, the position of the monitors can bedetermined, either relative to a reference or relative to each other.

In yet another alternative, a camera is attached to a monitor. Theposition of the camera can be determined from the output image of thecamera, by image analysis. The relative position between the monitorscan be calculated from the known relative position between the monitorand the corresponding camera. In one example, the relative position canbe calculated directly if a monitor can be seen in the output image of acamera which is attached to another monitor. In another example, therelative position of the monitors is calculated relative to a reference,and the relative position between the monitors is calculated from thepositions of these monitors relative to the reference.

A person who is viewing a monitor can be identified using a camera whichis attached to the monitor. When generating the image which is to bedisplayed on this monitor, the image generator 9 can generate the imagein accordance with the identity of the viewer, as explained above.

Incident light onto a monitor can be detected using a camera which isattached to the monitor. The intensity level of the ambient light can bedetermined from the incident light, in order to adjust the contrastand/or brightness of the monitor and/or of the image being displayed onthe monitor. Additionally or alternatively, unwanted reflections of theincident light onto the viewer can be determined. The brightness and/orcontrast of the monitor and/or the image can then be adjusted on thebasis of this information. The most important data can also be displayedin a region of the image in which the monitor does not produce unwantedreflections. The position of the monitor can also alternatively oradditionally be automatically adjusted so as to prevent the reflections,for example using drive actuators (not shown) which adjust the mountingof the monitor.

Actuators of the mounting can additionally or alternatively be used tocontinuously reposition the monitor to face a moving viewer and/or inorder to move the monitor into a desired position, such as an initialposition for the surgery. This initial position can be explicitlyprogrammed or can be automatically derived from the type and/or locationof the surgery.

The example embodiments which have been described above with referenceto the figures are purely illustrational and in no way limit the scopeof the present invention as defined in the following claims.

What is claimed:
 1. A system for image-guided surgery, comprising: aplurality of display devices; a position determinator for determining arelative position between the plurality of display devices; and an imagegenerator for generating images which are to be displayed by theplurality of display devices in accordance with the relative positionbetween the plurality of display devices, wherein the image generatorselectively generates a first image for display on a first displaydevice of the plurality of display devices and a second image differentthan the first image for display on a second display device differentthan the first display device responsive to a distance between the firstand second display devices being, based on the determined relativeposition, above a predefined threshold, wherein the image generatorselectively generates the second image for enlarged display spanning thefirst and second display devices responsive to the distance between thefirst and second display devices being, based on the determined relativeposition, less than the predefined threshold.
 2. The system of claim 1,further comprising: an adjustable mounting operatively coupled with thefirst display device, wherein the mounting comprises multiple elementsand wherein two adjoining elements of the adjustable mounting areconnected via an adjustable joint; and at least one sensor for detectinga state of the adjustable joint.
 3. The system of claim 1, furthercomprising: a marker device attached with the first display device,wherein the position determinator is configured to determine therelative position from a position of the marker device.
 4. The system ofclaim 1, further comprising: at least one camera configured to generatean output image of the plurality of display devices, wherein theposition determinator is configured to determine the relative positionfrom the output image of the at least one camera.
 5. The system of claim1, further comprising: a camera configured to generate an output imageand attached with the first display device, wherein the positiondeterminator is configured to determine the relative position from theoutput image of the camera.
 6. The system of claim 1, furthercomprising: an adjustable mounting operatively coupled with the firstdisplay device and comprising multiple elements, wherein two adjoiningelements of the adjustable mounting are connected via an adjustablejoint; and at least one actuator for adjusting a state of the adjustablejoint.
 7. The system of claim 1, wherein: the position determinatordetermines a relative position of each of the plurality of displaydevices relative to the another object other than the plurality ofdisplay devices; and the image generator generates the images for eachof the plurality of display devices depending on the relative positionof each of the plurality of display devices relative to the anotherobject other than the plurality of display devices.
 8. The system ofclaim 1, wherein: the image generator selectively generates an imagerepresenting a graphical user interface for display as the first imageon the first display device of the plurality of display devices and animage representing medical data for display as the second image data onthe second display device responsive to the distance between the firstand second display devices being, based on the determined relativeposition, above the predefined threshold, the image generatorselectively generates the image representing the medical data forenlarged display spanning the first and second display devicesresponsive to the distance between the first and second display devicesbeing less than the predefined threshold.
 9. The system of claim 8,wherein the first display device comprises a touch-sensitive surfacewhich is selectively functional responsive to the distance between thefirst and second display devices being, based on the determined relativeposition, above the predefined threshold.
 10. A method of generatingimages for a plurality of display devices in a system for image-guidedsurgery, the method comprising: determining a relative position betweenthe plurality of display devices; and generating images, which are to bedisplayed by the plurality of display devices in accordance with thedetermined relative position by: selectively generating a first imagefor display on a first display device of the plurality of displaydevices and a second image different than the first image for display ona second display device different than the first display deviceresponsive to a distance between the first and second display devicesbeing, based on the determined relative position, above a predefinedthreshold, and selectively generating the second image for enlargeddisplay spanning the first and second display devices responsive to thedistance between the first and second display devices being, based onthe determined relative position, less than the predefined threshold.11. The method of claim 10, further comprising determining the relativeposition from a state of at least one joint which connects adjoiningelements of a mounting device for the first display device.
 12. Themethod of claim 10, further comprising determining the relative positionfrom positions of one or more marker devices attached with the firstdisplay device.
 13. The method of claim 10, further comprisingdetermining the relative position from at least one output image of atleast one camera, wherein the at least one output image shows theplurality of display devices.
 14. The method of claim 10, furthercomprising determining the relative position from at least one outputimage of a camera which is attached with the first display device. 15.The method of claim 10, further comprising generating a drive signal fordriving at least one actuator in order to adjust a state of at least onejoint which connects two adjoining elements of an adjustable mountingwhich holds the first display device.
 16. The method of claim 10,further comprising: selectively generating an image representing agraphical user interface for display as the first image on the firstdisplay device of the plurality of display devices and an imagerepresenting medical data for display as the second image data on thesecond display device responsive to the distance between the first andsecond display devices being, based on the determined relative position,above the predefined threshold; and selectively generating the imagerepresenting the medical data for enlarged display spanning the firstand second display devices responsive to the distance between the firstand second display devices being less than the predefined threshold. 17.The method of claim 16, further comprising selectively operating atouch-sensitive surface of the first display device which is selectivelyfunctional responsive to the distance between the first and seconddisplay devices being, based on the determined relative position, abovethe predefined threshold.
 18. A non-transitory computer readable storagemedium storing a computer program which, when running on a computer orwhen loaded onto a computer, causes the computer to: determine arelative position between a plurality of devices; and generate imageswhich are to be displayed by the plurality of display devices inaccordance with the determined relative position by: selectivelygenerating a first image for display on a first display device of theplurality of display devices and a second image different than the firstimage for display on a second display device different than the firstdisplay device responsive to a distance between the first and seconddisplay devices being, based on the determined relative position, abovea predefined threshold, and selectively generating the second image forenlarged display spanning the first and second display devicesresponsive to the distance between the first and second display devicesbeing, based on the determined relative position, less than thepredefined threshold.
 19. The non-transitory computer readable storagemedium storing the computer program of claim 18 which, when running on acomputer or when loaded onto a computer, causes the computer to:selectively generate an image representing a graphical user interfacefor display as the first image on the first display device of theplurality of display devices and an image representing medical data fordisplay as the second image data on the second display device responsiveto the distance between the first and second display devices being,based on the determined relative position, above the predefinedthreshold; and selectively generate the image representing the medicaldata for enlarged display spanning the first and second display devicesresponsive to the distance between the first and second display devicesbased on the determined relative position being less than the predefinedthreshold.
 20. The non-transitory computer readable storage medium ofclaim 19, which when running on a computer or when loaded onto acomputer, causes the computer to selectively operate a touch-sensitivesurface of the first display device which is selectively functionalresponsive to the distance between the first and second display devicesbeing, based on the determined relative position, above thepredetermined threshold.